1. Field of the Invention
This invention relates to the design of reset pulse circuits.
2. Background Art
In complex electrical circuit designs, it is often necessary on power-up to set certain circuit nodes or circuit elements to a known state. For example, when the ON switch is enabled in computer circuits, the computer clocks and other counters need to be initiated, started or reset. Power-on reset circuits are also often required for dynamic random access memory (DRAM) operation. The reset function is most easily accomplished by an automatic pulse which executes immediately after power is turned on. The automatic reset circuit should only act immediately after power-up; accidental firing unnecessarily interrupts the use of the circuit. An effective reset circuit should not inadvertently misfire.
Prior art preset circuits are electronically cumbersome because they use discrete components to achieve these characteristics. The present invention is a device to perform the automatic reset function needed in electrical circuits, which it does with greater device efficiency. It is not dependent on discrete resistive and capacitive components that reside off-chip. The present invention eliminates external power-on circuits, prevents accidental resetting, and is more simple than prior art designs.
Typically, single pulse-type power-on reset signals are required to set critical circuit components to known states during power-on to guarantee the proper operation of a design. It is an object of the present invention to perform this automatic reset function.
It is also an object of the present invention to design an automatic reset signal circuit which self-protects from power source transients and glitches.
It is a further object of the present invention to design the automatic power-up reset signal without using discrete electrical components, i.e., to be an integrated circuit implementable design.